The present invention is based on a device and a method for detecting side collisions according to the species defined in the independent claims.
A device for detecting side collisions is known from the European Patent EP-667 822, in which a pressure sensor is located in a side section of a vehicle body. When a side collision occurs, the adiabatic pressure increase in the side section is evaluated for side-collision detection. The side section is substantially closed in this case. Adiabatic means that the amount of heat remains constant.
The device and the method according to the present invention for detecting side collisions having the features of the independent claims have the advantage over the related art that a temperature sensor located in the side section of the vehicle body is less complicated than a pressure sensor. This results in cost savings. Also, no filtering of noise signals, such as acoustic frequencies, is required. Furthermore, the device according to the present invention and the method of the present invention are robust and react to actual deformations of the vehicle body. Thus, the method and the device according to the present invention are less sensitive with respect to events (driving through potholes, driving over the curb or slamming of the door) that suggest a side collision, but are not supposed to trigger a restraint system.
By the measures and further refinements mentioned in the dependent claims advantageous improvements of the device and the method for side-collision detection according to the present invention are made possible.
It is particularly advantageous that the temperature sensor is designed as a micromechanical sensor, so that the temperature sensor is easy to manufacture in mass production. The micromechanical sensor could be an extremely precise temperature sensor.
By designing a housing around the temperature sensor in the side section of the vehicle it is protected against radiation, and the adiabatic effect is increased since the air surrounding the temperature sensor is better insulated.
Using an acceleration sensor also has the advantage that a plausibility signal is generated, which is used to check a triggering signal obtained as a result of the temperature-sensor measurement. In this way, undesired triggering decisions for a restraining device and unnecessary injuries are prevented and costs are saved for the user of a restraint system. As an alternative, it is also possible that the acceleration sensor makes the triggering decision, and the temperature sensor generates the plausibility signal.
Furthermore, it is advantageous that the restraint devices are only triggered if the absolute temperature change and a temperature gradient exceed specified threshold values. It is ascertained especially with the temperature gradient that the temperature increase is short-term, so that a warming as a result of the vehicle being exposed to sunlight does not lead to an undesired triggering.
Finally, it is also advantageous, on the one hand, that redundancy is obtained by arranging a plurality of temperature sensors in a side section of a vehicle and, on the other hand, a temperature sensor will in each case be located near a deformation location of the side section.